Application Report SBAAA March Revised April Analog FrontEnd Design for ECG Systems - PDF document

ApplicationReport SBAA160A–March2009–RevisedApril2010 AnalogFront-EndDesignforECGSystemsUsing Delta-SigmaADCs KarthikSoundarapandian,MarkBerarducci.........................................................DataAcquisitionProducts ABSTRACT Thisdocumentdiscussesthecharacteristicsofelectrocardiogram(ECG)signalsanddifferent approachesforECGsignalacquisition.Thetradeoffsbetweendifferentapproachesandtheeffectson overallsystemdesignarediscussed.Thereportalsoincludesdescriptionsofpotentialimplementationsof thefront-endarchitectureusingtheADS1258andADS1278andrespectivenoisemeasurementresults. Contents 1Introduction 2NatureoftheECGSignalandSystemDesignImplications..........................................................2 3SystemApproaches........................................................................................................3 4ECGAFEwithLow-Resolution(”16-bit)ADCs........................................................................4 5SimplifiedLow-CostECGAFEwith24-bitDelta-SigmaADCs.......................................................5 7SimultaneousSamplingMeasurementswiththeADS1278...........................................................9 8References.................................................................................................................10 ListofFigures 1ECGSignalCharacteristics................................................................................................2 2SystemApproachesBasedonADC 3TypicalSAR-BasedECGSignalChain(SequentialSampling).......................................................4 4
û\b-Based,Low-CostECGSignalChain(SequentialSampling).....................................................5 5
û\b-Based,Low-CostECGSignalChain(SimultaneousSampling)..................................................6 6TestSetupUsingtheADS1258 7MeasuredTimeDomainData.............................................................................................8 8TestSetupUsingtheADS1278...........................................................................................9 9ADS1278withSimulated2-mVCardiacTestInput...................................................................10 1Introduction Electrocardiogram(ECG)systemanalogfront-end(AFE)devicesaretypically off-the-shelfcomponentsfromvarioussemiconductorvendorsorcustom-designedasapplication-specific integratedcircuits(ASICs).ThecostsofanASICdesigncouldrunintomillionsofdollarsbythetimethe devicereachesfullproduction,andmaynotbepracticalformanysmall-andmedium-sizedcompanies. TheprimarycomponentsofatraditionaldiscreteECGAFEinclude amplifiersthatimplementactivefilters,andanalog-to-digitalconverters(ADCs). Alltrademarksarethepropertyoftheirrespectiveowners. 1 SBAA160A–March2009–RevisedApril2010 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated NatureoftheECGSignalandSystemDesignImplicationswww.ti.com RecenttechnologyadvancementshaveresultedinADCswithacombinationofspeeds,resolution,and powerthatwereimpossiblebefore.Atthesametime,thenecessityforlow-costandlow-powerECG machineshasincreased,imposingconstraintsonengineersanddesignerstomakesystemsmoreand moreaffordable.Thisarticleexamineshowtousethelatesthigh-performancedelta-sigma(
û\b)ADCs fromTexasInstrumentsascomponentsofanECGAFEsystem,anddiscusseshowtooptimizethecost ofanECGAFEfromasystemdesignperspective. 2NatureoftheECGSignalandSystemDesignImplications Thefirststepinanysystemdesignistofullyunderstandthesignalthatistobeprocessedbythesystem. ThisstepisespeicallytrueforanECGAFEsystem.Figure1showsthewidelyaccepteddetailsofthe ECGsignalasitappearsattheinputoftheECGmeasurementsystem(seeRef1).Itconsistsofthree components:theactual(differential)ECGsignal,thedifferentialelectrodeoffset,andthecommon-mode signal. TheactualdifferentialECGsignalthatappearsbetweentheelectrodesinanyleadconfigurationislimited to±5mVinmagnitudeand0.05Hzto150Hzinfrequency.ThemagnitudeofthisactualECGsignal, togetherwiththeresolutionrequiredfromtheECGsignal,determinesthedynamicrangerequirementof thefront-end.Thefrequencycontentofthissignaldeterminesthebandwidthrequirementsoftheanalog front-end. Theskin-electrodeinterfacegivesanadditionaldcoffsetofapproximately300mV.Thisoffsetmustbe manipulatedsuchthatthesignalchainisnotsaturated.Therearetwowaysofmanagingthisoffset, dependingonthetypeofADCusedinthesystem:eithereliminateitcompletelyorpreserveit.This applicationnoteanalyzestheadvantagesanddisadvantagesofbothmethods. Figure1.ECGSignalCharacteristics Inadditiontothesetwosignals,thehumanbodycanpickuplargeinterferencesignalsfrompowerlines, fluorescentlights,andsoforth.Thisinterferencecanmanifestitselfaseitheranormal-modesignalora common-modesignal.Normal-modeinterferencecanbemitigatedbyasoftware-implemented, 50-Hz/60-Hznotchfilter.Common-modeinterference,ontheotherhand,isgenerallycounteredinoneof threeways: •Increasingtheisolationofthegroundofthefront-endelectronicsfromtheearthgroundasmuchas possible; •Increasingthecommon-moderejectionofthesignalprocessingcircuitry(ontheorderof100dB); •Drivingthepatientbodywithanout-of-phasecommon-modesignal(alsocalledastherightlegdrive). OneoftheprimaryspecificationsofanECGfront-endistheinput-referrednoise.Itistypicallyspecifiedto belessthan30PVRMSfortheentiresystemoverabandwidthof150Hz(IEC60601-2-51,27).The frequencycontentofthesignaldeterminesthe3-dBcutofffrequenciesrequiredforthesystemfilters. 2 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SBAA160A–March2009–RevisedApril2010 SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated www.ti.comSystemApproaches Apartfromtheseissues,thesignalfromtheECGelectrodesusuallyhavemotionartifactsandpacer pulses.Theseadditionalsourcesofinterferencemustberemovedbyusingappropriatefiltering,eitherin theanalogdomain(beforetheADC)orinthedigitaldomain(aftertheADC).Typically,ECGmachines haveameanstodetectthepresenceofpacemakers.Pacerdetectioncanbedoneeitherbyusing dedicatedhardwareorbyusingsoftware.Thesoftwareapproachrequiresthefront-endtohavehigher bandwidthandtheADCtohaveahighersamplingrate.However,oneoftheadvantagesofusing softwarepacedetectionisthataspacemakerdevicesevolve,thedetectionthresholdscanbedynamically changedviasoftware,insteadofhavingtomodifythesystemhardware. 3SystemApproaches 3.1Low-Resolution(”16-bit)ADCsvsHigh-Resolution(24-bit)ADCs BasedontheresolutionoftheADCusedinthesignalchain,therearetwodifferentapproachesto processingtheECGsignal.Oneapproachistouselow-noiseamplifiersandtogaintheinputsignal significantly(approximately500),andthususealow-resolution(approximately16-bit)ADC,asshownin Figure2a.Inthiscase,caremustbetakensothatthenoiseoftheamplifierthatgetsamplifieddoesnot dominatetheoverallsystemnoise.Theotherapproachwouldbetousealowergain(approximately5) andahigh-resolution(approximately24-bit)ADC,asshowninFigure2b.Inbothapproaches,the noise-freedynamicrangeattheADCoutputremainsthesame. Figure2.SystemApproachesBasedonADCResolution Theotherwaytoconsiderthisresultisthatthesystemnoisereferredtotheinputisthesameinboth cases.Therefore,therecordedsignalqualitywouldnotbecompromised.However,adecisionaboutusing oneoftheseapproachessignificantlyaffectsthespecificationsoftheindividualcomponentsofthesystem, andconsequentlytheoverallcost,asexplainedinthenextsection.Thehigh-resolutionADCapproach significantlyreducestherequiredhardware,whichimpliesbothalowercostandlowerpower requirements. 3.2SequentialSamplingvsSimultaneousSampling TwodifferentsolutionscanbeenvisionedbasedonthespeedoftheavailableADCswiththerequired resolution.OneapproachistouseadedicatedADCforeachchannel,therebysamplingallleads simultaneously.TheotherapproachistomultiplextheleadsignalssothatasingleADCcanbeusedto digitizealltheleadssequentially.Sequentialsampling,asitsounds,shouldreducetheamountof front-endhardware.Itbecomesquiteobvious,though,thatthespeedoftheADCinasequentialsampling architectureshouldbesignificantlyhigherthaninasimultaneoussamplingapproach.Higher-speedADCs, inturn,tendtoconsumemuchmorepower.Asaresult,itisnotnecessarythatthesequentialsampling solutionbeoptimizedforpower.ThesettlingtimeofthemultiplexerinfrontoftheADCalsoplaysa significantroleindeterminingtherequiredspeedoftheADCsinthisapproach.Onemustbeaware, however,thatwhenusingasequentialsamplingapproach,thesamplesfromdifferentchannelsare skewedintime.Softwarealgorithmsarethenusedtointerpolatetheacquireddatabetweensamplingfor waveformre-construction. 3 SBAA160A–March2009–RevisedApril2010 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated ECGAFEwithLow-Resolution(”16-bit)ADCswww.ti.com Tosummarize,theanalogfront-endhardwareforanECGsystemcouldbeminimizediftherewasanADC withaveryhighresolution(approximately24bits)andahigh-speed(approximately100ksps). Fortunately,suchasolutionisfeasibleusingthelatesthigh-speed,high-resolutiondelta-sigmaADC offeringsfromTexasInstruments.Thenextsectionexplainsthedifferencesandsavingsinhardwareby usinga24-bit,delta-sigmaADC. 4ECGAFEwithLow-Resolution(”16-bit)ADCs Figure3showsatypicalECGAFEwithsequentialsamplingusinga16-bitconverter. Figure3.TypicalSAR-BasedECGSignalChain(SequentialSampling) Thefirstblockisintendedforpatientprotectionanddefibrillationpulseclamping,whichcouldinclude high-valueresistorsoranyotherkindofisolationcircuitry.Theleadselectioncircuitrydeterminesthe variouselectrodecombinationstobemeasuredbasedontheEindhoventriangleandWilsoncentral terminal(seeRef1formoreinformation).TheECGelectrodesarehigh-impedancesignalsources; therefore,theyarefedintotheinstrumentationamplifiers,whichhaveaveryhighCMRR(greaterthan 100dB)andahighinputimpedance(greaterthan10MŸ).BeforetheECGsignalispassedtotheADC,it mustbeamplifiedsothattheentiredynamicrangeoftheADCisused,asillustratedinFigure2a. AtypicalADCfull-scalevoltageisapproximately2.5V,whichimpliesagainof500(assuminga5-mV inputsignal).Thetotalgainisdistributedbetweentheinstrumentationamplifier(INA)andanadditional gainamplifier.GainisaddedtotheINAinsuchawaythattheelectrodedcoffsetdoesnotsaturatethe INA.TheactualvalueofthisgaindependsontheoperatingvoltageoftheINA.Withthelatesttrendsof analogsupplyvoltageat5V,themaximumINAgaincanbeintherangeof5to10.Atthispoint,thedc componentmustberemovedbeforeanyfurthergaincanbeintroduced.Thus,ahigh-passfilter(HPF) withacornerfrequencyof0.05Hzisadded.Oncethedccomponentisremoved,thesignalisgainedup againwithanotheramplifier.Itshouldbenotedthattheamplifiersusedforthesegainstagesmustbevery lownoise,sothattheydonotdominatethenoiseofthesystem.Additionally,theseamplifiersmustbelow power(forbattery-poweredsystems).Thiscombinationrequirementforlowpowerandlownoise increasesthecostoftheprecisionampsrequiredbythesystem.Thisgainstageisfollowedbyan antialiasingfilter.Nyquistrateconverterssuchassuccessiveapproximationregister(SAR)ADCsmust haveaverysharpantialiasingfiltertoavoidaliasingout-of-bandnoise.Typically,afourthorderorhigher activelow-passfilter(LPF)isused.TheLPFblockisfollowedbyamultiplexerblock(mux)thatfeedsinto theADC. Itcanbeseeninthistypeofsystemthatthereisasignificantamountofanalogsignalprocessingthat occursbeforethesignalisdigitized,includinggainandfiltering.Additionally,signalprocessinginthe analogdomainlimitsflexibility.Often,thegain,bandwidth,anddctracking(thatis,baselinewandering) arerequiredtobeoptimized,andarebetterservedinthedigitaldomain.Sincedigitalsignalprocessingis relativelylowercostandprovidesagreatdealofflexibility,itisbeneficialtomovethesignalprocessingto thedigitaldomain.Thesystemdescribedinthenextsectionfollowsthisapproach. 4 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SBAA160A–March2009–RevisedApril2010 SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated www.ti.comSimplifiedLow-CostECGAFEwith24-bitDelta-SigmaADCs 5SimplifiedLow-CostECGAFEwith24-bitDelta-SigmaADCs Figure4showsthesameECGfront-endwithadelta-sigmaconverterimplemented.Delta-sigma convertersareknowntogiveveryhigh-resolutionperformance(greaterthan20bits)usingoversampling andnoise-shapingprinciples(seeRef2).Traditionally,delta-sigmaADCspeedshavebeenrestrictedto samplingratesofseveralkilohertz.Recenttechnologyadvancementshaveledtodelta-sigmaADCswith excellentacanddcperformance,withsamplingratesuptohundredsofkilohertz(seeRef3,forexample). Figure4.
û\b-Based,Low-CostECGSignalChain(SequentialSampling) Figure4showssuchadelta-sigmaADC(theADS1258)usedfortheECGfront-end.TheADS1258isan industry-leading,24-bitconverterfromTexasInstrumentsthatoffersanimpressivecombinationoflow latency,highspeed,andnoiseperformance.TheADS1258provides1.8kSPSperchannelwith21.6 effectivebits,makingitanidealfitforECGapplications.BycomparingFigure3andFigure4,itcanbe seenthatthereisasignificantreductioninhardware,whichimpliesbothlowercostandlowerpower. Threeblocks(includingthehigh-passfilter,dcblockingfilter,gainstage,andasteep,activelow-pass filter)areeliminated.TheADS1258hasanintegratedmuxaswell,allowinguptoeightdifferentialinputs andtherebyeliminatingtheneedforanexternalmux.Inadditiontoofferingtheadvantageofhigher resolution,thedelta-sigmaADCssignificantlyrelaxtheantialiasingrequirementsbeforetheADC.The complicatedactiveantialiasingfilters,whichcouldrequireseveralamplifierstoimplement,canbereplaced byasimple,single-poleRCfilter.Thedcblockinghigh-passfilteriseliminatedaswell,becausethe inherentnoiseoftheADCissignificantlylowerthantheprevioussolution(Figure2b).Inthisway,thedc informationisnotlost,andthevariousfilterscanalsobeimplementeddigitally.Digitalfilter implementationalsogivesthedesignerflexibilitytouseadaptivedcremovalfiltersforoverallfaster responseandbetterrejectionofbaselinewandering. ThenoiseoftheADS1258,whenreferredtotheinputofthesystem,gives1PVRMSto3PVRMSdepending ontheoutputdatarate,withanINAgainof4.ThisnoiseiswellwithincommercialECGrequirements. 5 SBAA160A–March2009–RevisedApril2010 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated SimplifiedLow-CostECGAFEwith24-bitDelta-SigmaADCswww.ti.com Beingasequentialsolution,theADS1258-basedAFEhasaskewof42Psbetweenchannels.Formost applicationsmthisskewmaybeacceptable;however,forcertainapplicationssuchas electroencephalography(EEG)andvectorimagingsystems,therequiredskewislessthan25Ps.Inthese applications,asimultaneoussampling,high-resolutionADCapproachisagoodfit.Figure5showsthe signalchainforsimultaneoussamplingwithADS1278.TheADS1278isauniquedeviceinTexas Instruments'
û\bportfolio,offeringaveryhighlevelofintegration.Itintegrateseightdedicated24-bit delta-sigmaADCsandeightdigitaldecimationfiltersinasingle,64-pin,TQFPpackage. Figure5.
û\b-Based,Low-CostECGSignalChain(SimultaneousSampling) 6 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SBAA160A–March2009–RevisedApril2010 SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated www.ti.comSequentialSamplingMeasurementswiththeADS1258 6SequentialSamplingMeasurementswiththeADS1258 AtestconfigurationasshowninFigure6isusedtoevaluatetheADS1258forECGmeasurement applications.ThemeasurementresultsaresummarizedinTable1. Figure6.TestSetupUsingtheADS1258 Table1.MeasuredInput-ReferredNoiseResults ADS1258(1) Noise EffectiveDataRate (PVRMS,input DRATE[1:0] DataRate(SPS) (16-ChannelSPS) lead-referred) 11 17480 1093 3 10 12372 773 2.2 1 5704 357 1.5 0 1807 113 1.2 (1)ADS1258parameters:fCLKIN=16.257MHz,DLY=010,CHOP=0. 7 SBAA160A–March2009–RevisedApril2010 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated SequentialSamplingMeasurementswiththeADS1258www.ti.com Inthissetup,aDynatechNevadaECGsignalsimulatorwasusedasthesignalsource.TheINA121was selectedbecauseitofferslowcurrentandvoltagenoise.The100-kŸinput(safety)resistorswereusedon theINA121inputsforallmeasurements.AnOPA227opampusedintheADS1258muxoutputloop providesslightlybetternoiseperformanceandbetteroffsetmatchbetweenchannelscomparedtoa bypassconnection(nobuffer).ThenoisedatawereobtainedwithshortedinputsoftheINA121withthe 100-kŸseriesresistorsinplace.Figure7showsthetimedomaincapturedattheADS1258output. Figure7.MeasuredTimeDomainData 8 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SBAA160A–March2009–RevisedApril2010 SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated www.ti.comSimultaneousSamplingMeasurementswiththeADS1278 7SimultaneousSamplingMeasurementswiththeADS1278 ThetestconfigurationshowninFigure8wasusedtoevaluatetheADS1278forECGmeasurements.The Agilent33120Asignalgeneratorsourcesa2-mVpeakcardiactestwaveform.The100-kŸinput(safety) resistorsareusedontheINA121inputsforalltestmeasurements.TheINA121wasselectedbecauseof thecombinationofbothlowvoltageandlowcurrentnoise.TheINA121gainwassetto4andtheoutputis bandlimitedto150HzbeforetheADC.TheINA121referencepinissetto2.5Vtoshiftthe common-modeofthesignaltothemid-supplyleveloftheADC. Figure8.TestSetupUsingtheADS1278 ThenegativeinputsoftheADCsarelikewiseshiftedto+2.5V,allowingbipolardifferentialECGinput swings.TheADS1278wasconfiguredintheLow-SpeedMode(thatis,withadatarateequalto 10kSPS).Thismodedissipatesonly7mW/channelwithonly8-PVRMSnoiseoverthe5-kHzbandwidth. Datawereobtainedfromeightchannelssimultaneously. Theinputresistorscontribute2.9-PVRMSnoiseoverthe150-Hzbandwidth(referredtotheADCinputs). TheINA121addslessthan4-PVRMSnoisetotheinputoftheADC.Thenoiseoftheinputresistorsand thatoftheINA121combinewiththenoiseoftheADS1278,increasingtheADCoutputnoisefrom8PVto 9.5PV(ADCoutput-referrednoise). 9 SBAA160A–March2009–RevisedApril2010 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated Referenceswww.ti.com TheADS1278noisedatawereobtainedwithallchannelssimultaneouslyconvertingandwiththeINA121 inputsshorted(withthe100-kŸresistorsinplace).Table2showstheinput-referrednoiseoftheADS1278 samplingat10kSPS,andalsoshowstheinput-referrednoisewiththeADCdatafilteredwithasimple movingaverageofx4andwithmovingaverageofx8.Post-filteringtheADCdatainthiswayis straightforwardtoimplement,andreducesthenoiseapproximatelybythesquarerootoftheaveraging factorwhilereducingthedataratebythesamefactorsof4and8(decimationintime). Table2.ADS1278SimultaneousSamplingNoisefor Figure8(ShortedInputs) Input-ReferredNoise LeadInput-Referred DataRate (PVRMS) Noise(PVPP) 10.0kSPS 2.4 15.7 2.50kSPS 1.4 9.5 1.25kSPS 1.2 7.9 Theinput-referrednoiseoftheADS1278testcircuitwithpost-filteringislessthan10PVPP.Thisamountof noiseiswithinthecustomarystandardsforhigh-resolutionECGsystems. Figure9showstheADS1278outputdatawithasimulated2-mVpeakcardiactestinput. Figure9.ADS1278withSimulated2-mVCardiacTestInput 8References 1.Webster,J.G.(1998).Medicalinstrumentation:Applicationanddesign(3rdedition).NewYork:Wiley andSons. 2.Norsworthy,S.R.,Schreier,R.S.,andTemes,G.C.(1997).Delta-sigmadataconverters:Theory, designandsimulation.NewYork:IEEEPress. 3.ADS1258:16-Channel,24-BitAnalog-to-DigitalConverter.ProductdatasheetSBAS297C.Available fordownloadatwww.ti.com/ads1258. 4.ADS1278:Octal,128-kHz,SimultaneousSampling24-BitDelta-SigmaAnalog-to-DigitalConverter. ProductdatasheetSBAS367C.Availablefordownloadatwww.ti.com/ads1278. 10 AnalogFront-EndDesignforECGSystemsUsingDelta-SigmaADCs SBAA160A–March2009–RevisedApril2010 SubmitDocumentationFeedback Copyright©2009–2010,TexasInstrumentsIncorporated IMPORTANTNOTICETexasInstrumentsIncorporatedanditssubsidiaries(TI)reservetherighttomakecorrections,modifications,enhancements,improvements,andotherchangestoitsproductsandservicesatanytimeandtodiscontinueanyproductorservicewithoutnotice.Customersshouldobtainthelatestrelevantinformationbeforeplacingordersandshouldverifythatsuchinformationiscurrentandcomplete.AllproductsaresoldsubjecttoTI’stermsandconditionsofsalesuppliedatthetimeoforderacknowledgment.TIwarrantsperformanceofitshardwareproductstothespecificationsapplicableatthetimeofsaleinaccordancewithTI’sstandardwarranty.TestingandotherqualitycontroltechniquesareusedtotheextentTIdeemsnecessarytosupportthiswarranty.Exceptwheremandatedbygovernmentrequirements,testingofallparametersofeachproductisnotnecessarilyperformed.TIassumesnoliabilityforapplicationsassistanceorcustomerproductdesign.CustomersareresponsiblefortheirproductsandapplicationsusingTIcomponents.Tominimizetherisksassociatedwithcustomerproductsandapplications,customersshouldprovideadequatedesignandoperatingsafeguards.TIdoesnotwarrantorrepresentthatanylicense,eitherexpressorimplied,isgrantedunderanyTIpatentright,copyright,maskworkright,orotherTIintellectualpropertyrightrelatingtoanycombination,machine,orprocessinwhichTIproductsorservicesareused.InformationpublishedbyTIregardingthird-partyproductsorservicesdoesnotconstitutealicensefromTItousesuchproductsorservicesorawarrantyorendorsementthereof.Useofsuchinformationmayrequirealicensefromathirdpartyunderthepatentsorotherintellectualpropertyofthethirdparty,oralicensefromTIunderthepatentsorotherintellectualpropertyofTI.ReproductionofTIinformationinTIdatabooksordatasheetsispermissibleonlyifreproductioniswithoutalterationandisaccompaniedbyallassociatedwarranties,conditions,limitations,andnotices.Reproductionofthisinformationwithalterationisanunfairanddeceptivebusinesspractice.TIisnotresponsibleorliableforsuchaltereddocumentation.InformationofthirdpartiesmaybesubjecttoadditionalResaleofTIproductsorserviceswithstatementsdifferentfromorbeyondtheparametersstatedbyTIforthatproductorservicevoidsallexpressandanyimpliedwarrantiesfortheassociatedTIproductorserviceandisanunfairanddeceptivebusinesspractice.TIisnotresponsibleorliableforanysuchstatements.TIproductsarenotauthorizedforuseinsafety-criticalapplications(suchaslifesupport)whereafailureoftheTIproductwouldreasonablybeexpectedtocauseseverepersonalinjuryordeath,unlessofficersofthepartieshaveexecutedanagreementspecificallygoverningsuchuse.Buyersrepresentthattheyhaveallnecessaryexpertiseinthesafetyandregulatoryramificationsoftheirapplications,andacknowledgeandagreethattheyaresolelyresponsibleforalllegal,regulatoryandsafety-relatedrequirementsconcerningtheirproductsandanyuseofTIproductsinsuchsafety-criticalapplications,notwithstandinganyapplications-relatedinformationorsupportthatmaybeprovidedbyTI.Further,BuyersmustfullyindemnifyTIanditsrepresentativesagainstanydamagesarisingoutoftheuseofTIproductsinsuchsafety-criticalapplications.TIproductsareneitherdesignednorintendedforuseinmilitary/aerospaceapplicationsorenvironmentsunlesstheTIproductsarespecificallydesignatedbyTIasmilitary-gradeor"enhancedplastic."OnlyproductsdesignatedbyTIasmilitary-grademeetmilitaryspecifications.BuyersacknowledgeandagreethatanysuchuseofTIproductswhichTIhasnotdesignatedasmilitary-gradeissolelyattheBuyer'srisk,andthattheyaresolelyresponsibleforcompliancewithalllegalandregulatoryrequirementsinconnectionwithsuchuse.TIproductsareneitherdesignednorintendedforuseinautomotiveapplicationsorenvironmentsunlessthespecificTIproductsaredesignatedbyTIascompliantwithISO/TS16949requirements.Buyersacknowledgeandagreethat,iftheyuseanynon-designatedproductsinautomotiveapplications,TIwillnotberesponsibleforanyfailuretomeetsuchrequirements.FollowingareURLswhereyoucanobtaininformationonotherTexasInstrumentsproductsandapplicationsolutions: Audiowww.ti.com/audio DataConverters Automotivewww.ti.com/automotive DLP®Products Communicationsand TelecomDSPdsp.ti.com Computersand ClocksandTimers ConsumerElectronics Interfaceinterface.ti.com Energywww.ti.com/energy Logiclogic.ti.com Industrialwww.ti.com/industrial PowerMgmt Medicalwww.ti.com/medical Microcontrollersmicrocontroller.ti.com Securitywww.ti.com/security RFIDwww.ti-rfid.com Space,Avionics& RF/IFandZigBee®Solutions VideoandImaging Wirelesswww.ti.com/wireless-apps MailingAddress:TexasInstruments,PostOfficeBox655303,Dallas,Texas75265Copyright©2010,TexasInstrumentsIncorporated